Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, the Netherlands.
Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, the Netherlands.
Appl Ergon. 2021 Sep;95:103450. doi: 10.1016/j.apergo.2021.103450. Epub 2021 May 8.
External human-machine interfaces (eHMIs) may be useful for communicating the intention of an automated vehicle (AV) to a pedestrian, but it is unclear which eHMI design is most effective. In a crowdsourced experiment, we examined the effects of (1) colour (red, green, cyan), (2) position (roof, bumper, windshield), (3) message (WALK, DON'T WALK, WILL STOP, WON'T STOP, light bar), (4) activation distance (35 or 50 m from the pedestrian), and (5) the presence of visual distraction in the environment, on pedestrians' perceived safety of crossing the road in front of yielding and non-yielding AVs. Participants (N = 1434) had to press a key when they felt safe to cross while watching a random 40 out of 276 videos of an approaching AV with eHMI. Results showed that (1) green and cyan eHMIs led to higher perceived safety of crossing than red eHMIs; no significant difference was found between green and cyan, (2) eHMIs on the bumper and roof were more effective than eHMIs on the windshield, (3) for yielding AVs, perceived safety was higher for WALK compared to WILL STOP, followed by the light bar; for non-yielding AVs, a red bar yielded similar results to red text, (4) for yielding AVs, a red bar caused lower perceived safety when activated early compared to late, whereas green/cyan WALK led to higher perceived safety when activated late compared to early, and (5) distraction had no significant effect. We conclude that people adopt an egocentric perspective, that the windshield is an ineffective position, that the often-recommended colour cyan may have to be avoided, and that eHMI activation distance has intricate effects related to onset saliency.
外部人机界面（eHMI）可用于向行人传达自动驾驶车辆（AV）的意图，但尚不清楚哪种 eHMI 设计最为有效。在一项众包实验中，我们研究了以下因素对行人和即将让行或不让行的 AV 交叉口的感知安全性的影响：（1）颜色（红、绿、青）；（2）位置（车顶、保险杠、挡风玻璃）；（3）信息（走、停、将停、不停、灯带）；（4）激活距离（距行人 35 或 50 米）；（5）环境中是否存在视觉干扰。参与者（N=1434）在观看 276 个接近中的 AV 的视频片段中的随机 40 个片段时，必须在感到安全时按下按键以穿过马路。结果表明：（1）绿色和青色 eHMI 比红色 eHMI 更能提高穿越的感知安全性；绿色和青色之间没有显著差异；（2）保险杠和车顶的 eHMI 比挡风玻璃上的 eHMI 更有效；（3）对于让行的 AV，与 WILL STOP 相比，WALK 更能提高感知安全性，其次是灯带；对于不让行的 AV，红灯与红色文本具有相似的效果；（4）对于让行的 AV，红灯在早期激活时比晚期激活时导致更低的感知安全性，而绿色/青色 WALK 在晚期激活时比早期激活时导致更高的感知安全性；（5）干扰没有产生显著影响。我们得出结论，人们采用自我中心的视角，挡风玻璃是一个无效的位置，通常推荐的青色可能需要避免，并且 eHMI 的激活距离与起始显著性有关，具有复杂的影响。
